To cite SightabilityModel in publications use:

Fieberg JR (2012). “Estimating Population Abundance Using Sightability Models: R SightabilityModel Package.” Journal of Statistical Software, 51(9), 1–20. https://www.jstatsoft.org/v51/i09/.

Corresponding BibTeX entry:

  @Article{,
    title = {Estimating Population Abundance Using Sightability Models:
      {R} {SightabilityModel} Package},
    author = {John R. Fieberg},
    journal = {Journal of Statistical Software},
    year = {2012},
    volume = {51},
    number = {9},
    pages = {1--20},
    url = {https://www.jstatsoft.org/v51/i09/},
  }